Circuit-interrupting apparatus



Feb. 23, 1943. w, KAUFMANN l CIRCUIT INTERRUPTING APPARATUS 3 Sheets-Sheet l Filed Aug. l1, 1959 Fig. z

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Feb. 23, 1943. w. KAUFMAN-N CIRCUIT INTRRUPTING APPARATUS 3 Sheets-Sheet 2 Filed Aug. ll, 1959 INVENTOR Wer/7er Kay/mann. qQ/Y h ATTORN WITNESES:

Feb. 23, 1943. w. KAUFMANN CIRCUIT INTERRUPTING APPARATUS Filed Aug. 11, 1939 3 Sheets-Sheet 5 INVENToR We/'Wr Kaz/fm @f7/7.

ATTORBEY WITNESS ES:

Patented Feb. 23, 1943 UNiTED STATES PATENT @FENCE CIRCUIT-INTERRUPTING APPARATUS Application August 11, 1939, Serial No. 289,535 In Germany August 12, 1938 7 Claims.

The inventionl relates to circuit-interrupting devices and more particularly to a high capacity circuit breaker arrangement for use in electrical transmission or distribution systems.

The removal ofv short-circuit arcs on transmission or distribution lines in the shortest possible time reduces damage to the lines and apparatus connected thereto. It has been found that a very high percentage of such disturbances completely disappear within a fraction of a second after the. circuit is interrupted, so that the circuit can be reclosed immediately thereafter with little danger' of the arc restriking. This is because most of the disturbances which occur are air short-circuits which completely disappear uponv interruption of the circuit, and are not apt to restrike because the hot arc gases lose their conductivity in a small fraction of a second The circuit should be interrupted and reestablished in the shortest time that is safely permissible, in order to maintain continuity of service and to prevent loss of synchronism in the system. Under such conditions of operation, the motors in the system will continue to run and the lights merely blink; and a very large percentage-approximately 80%-of all disturbances are eliminated in this manner and kept from the consumer.

In attempting to obtain the short time interval mentioned with circuit breakers of conventional design, considerable difficulties have been encountered with the mechanical reversal of the switching elements.

It is accordingly an object of the invention to provide an improved circuit-interrupting apparatus or short-circuit extinguisher which will reliably and satisfactorily interrupt and reestablish the circuit in the desired short and safe time interval.

Another object of the invention is the provision ci an improved circuit-interrupting apparatus which is operable upon the occurrence of a disturbance, such as a short-circuit in the line, to interrupt the circuit and immediately thereafter, that is approximately in a time interval of a fraction of a second after interruption, cause a reclosing of the circuit.

Another object of the invention is the provision of an improved circuit-interrupting apparatus or short-circuit extinguisher which is operable upon the occurrence of a disturbance, such a short-circuit, to quickly interrupt the circuit by one set of contacts, and in a very short time interval thereafter reclose the circuit by a second set of contacts.

In accordance with one embodiment of the invention, the circuit breaker or short-circuit extinguisher comprises a circuit interrupter which is operable upon the occurrence of a disturbance, such as a short-circuit, to quickly interrupt the circuit, and another switching device is arranged to automatically reclose the circuit immediately thereafter while the interrupter is open. The switching device is preferably an air-break switch associated with the circuit interrupter and interlocked therewith to automatically close after the interrupter opens.

A single short-circuit extinguisher, as described above, can be arranged to protect one or more outgoing lines, each having its own individual circuit interrupter therein for opening the line which remains short-circuited after the shortcircuit extinguisher has opened and reclosed the main supply circuit.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description of one embodiment thereof when read in conjunction with the accompanying drawings, in which:

Figure 1 is a diagrammatic view of the shortcircuit extinguisher or circuit breaker of the present invention, feeding several outgoing lines, each having its individual circuit interrupter therein;

Fig. 2 is a sectional view of the circuit breaker or short-circuit extinguisher constructed in accordance with the invention, the control devices and circuits being shown diagrammatically, and the extinguisher being shown in the normal circuit closed position;

Fig. 3 is a view similar to Fig. l showing the positions of the parts when the interrupter has interrupted the circuit and the air-break switch is being released to reclose the circuit;

Fig. 4: is a view similar to Fig. l showing the positions of the parts after the device has reclosed the circuit; and,

Fig. 5 is a fragmentary sectional view of the circuit breaker taken at right angles to the section of Fig. 2 substantially along the line V-V of Fig. 2.

Referring to the drawings, the reference numeral l designates a supporting insulator of vitreous insulating material, such as porcelain, for supporting the high-voltage circuit breaker or short-circuit extinguisher of the present invention. The supporting insulator is mounted on a base 9 and has a cup-shaped terminal member I I of conducting material rigidly secured to its upper end. This terminal member forms the lower terminal of the circuit-interrupting device, and has a stationary contact I3 mounted therein which constitutes the fixed contact of the interrupting device.

A tubular casing I5 of strong insulating material is mounted at its lower end on the cupshaped terminal member I I, and this tubular casing has a generally spherical hollow metal head I1 secured to its upper end. The tubular casing I5 is preferably secured to the terminal member II and head I1 in a iiuid-tight manner, as, for example, by its having a screw-threaded engagement with the terminal member and head.

A movable Contact member I9 in the form of a bar or rod of conducting material is mounted for vertical movement in the casing I5 and hollow metal head I1, and is guided for vertical movement therein by means of a guide member 2| secured in the neck of the head I1. The movable contact I9 is movable upwardly to open circuit position away from the cooperating stationary contact I3, and is movable downwardly to closed circuit position in engagement with the contact I3 by a mechanism which will be hereinafter described.

An operating shaft 23 extends transversely through the hollow metal head I1, being rotatably mounted in suitable bearings 25 (Fig. 5) formed on the opposite sides of the head I1. An operating lever 21 is rigidly secured to the shaft inside of the head and is connected at its free end to the upper end of the movable contact member I9 by means of a slot 29 formed in the lever 21, which engages a transverse pin 3| carried by the upper end of the movable contact member I9.

The circuit-interrupting device is electrically connected in amain circuit represented by the lines 33 and 35. The line 33 is electrically connected to the upper terminal 31 of the interrupting device, and the line 35 is electrically connected to the lower terminal member Il. The lower terminal I I is directly electrically connected to the stationary contact I3, and the upper terminal 31 is electrically connected in any suitable manner, as, for example, by a exible shunt conductorY or a sliding contact means, (not shown), to the movable contact member I9.

An arc-extinguishing means of any suitable type is provided within the interrupting chamber 39 and the tubular casing I5 for quickly extinguishing the arc drawn between the contacts I9 andV I3 during interruption of the circuit. The arc-extinguishing means may be of any well known type, as, for example, a fluid 4I, such as water or oil, contained within the chamber 39 and casing I5, in which the contacts are immersed, and/or a known type of arc-extinguishing structure of the Xed or expansion type may be associated with the contact means. The arcextinguishing means may also be of the fluid blast or compressed air-blast type, if desired.

For reclosing the circuit following a circuit interruption, an additional switching device is provided which comprises an air-break switch indicated generally at 43 associated with the circuitinterrupting device. `The switch 43 comprises a switch blade 45 which is rigidly mounted at one end inside of the head I1 on a shaft 41 extending transversely through the hollow spherical head I1. The switch blade is movable about the axis of the shaft 41 into and out of engagement with a cooperating fixed contact 49 which is mounted and closing movement of the switch blade 45.

The switching device 43 is electrically connected in the circuit in parallel relation to the contacts I3 and I9 of the circuit-interrupting device. The upper xed contact 49 of the switch is connected to the line 35 by means of a conductor 51, and the switch blade 45 is electrically connected to-y the upper terminal 31 of the circuit-interrupting device in any suitable manner, as, for example, by means of a flexible shunt conductor (not shown).

A mechanical actuating mechanism is provided for actuating the movable contact member I9 of the circuit-interrupting device and the switch blade 45. For actuating the movable contact member I9 of the circuit interrupter, there is provided a tension operating spring 59 which is coiled about the operating shaft 23, its ends being engaged with projections 6I formed in the head I1, and its central portion being engaged in a notch provided therefor in the operating lever 21 of the interrupting device. The spring 59 biases the operating shaft 23 and lever 21 in a counterclockwise direction to move the movable contact member I9 to open circuit position. The movable contact member I9 is normally adapted to be held in closed circuit position against the bias of the operating spring 59 by a pivoted latch 63, which is pivotally mounted in a slot 65 in the side of the head I1, and is biased to latching position by means of a spring 61. The pivoted latch 63 normally engages a latch projection 69 formed integral with the hub end of the operating lever 21 of the circuit-interrupting device. When the latch 63 is in latching engagement with the projection 69, the latch 53 is prevented from being moved in a clockwise direction under the influence of the opening force of the operating spring 23, by means of a projection 1I formed on the pivoted latch 63 which engages the upper edge of the slotted opening 65 in the head I1.

AThe latch 63 is adapted to be moved in a counterolockwise direction to released position to release the operating lever 21 and cause the operating spring to move the contact member I9 to open circuit position, by an overload trip device 13 which comprises an electromagnetic trip coil 15 and a movable trip armature or trip plunger 11, which is pivotally connected to the pivoted latch 93 at its upper end. The trip coil 15 is energized in accordance with the current flow in the circuit 33-35 by means of a conventional current transformer 19 coupled to the line 33.

The switch blade 45 of the switching device is adapted to be actuated to closed circuit position by means of an operating spring 8I, which is coiled about the shaft 41, and has its free ends engaging projections 83 formed on the inner surface of the hollow head I1 and its central portion engaged in a notch provided therefor in the switch blade 45. The spring 8l acts to bias the switch blade 45 in a clockwise direction to closed circuit position. The switch blade 45 is normally held in open circuit position, as shown in Fig. 2, by means of a pivoted double arm latch 85, one arm of which engages a latch projection or notch 81 formed in the hub of the switch blade 45.

The switching device 43 is arranged to automatically reclose the circuit comprising the lines 33 and 35 immediately after interruption of the circuit by the interrupting device; that is, after a short interval of time suiicient to insure that the short-circuit arc will not restrike when the circuit is reclosed. For most instances this short time interval is of the order of a fraction of a second, as most air short-circuits will completely disappear and will not restrike after this interval of time.

For the purpose of causing the switch device 43 to automatically reclose the circuit immediately after interruption of the circuit, there is provided a cam projection 89 formed on the operating lever 21 which is disposed to engage the lower arm of the switch latch to release the switch latch 85 when the movable contact member I9 reaches open position.

In order to introduce the desired short time interval between interruption of the circuit and automatic reclosing of the circuit by the switch device 43, a dashpot device 9| is provided which acts to retard the final portion of the opening movement of the movable contact member I9 prior to the time that the switch latch 85 is released. The dashpot device 9| comprises a cylinder 93 mounted in the upper end of the hollow head I1, and a dashpot piston and plunger 95 movable in the cylinder 93. The cylinder 93 is provided with a slow-leak passage 91 so that the upward movement of the plunger 95 is retarded by the air in the cylinder above the piston as it leaks slowly out of the passage 91. The plunger 95 of the dashpot device is disposed in a position to be engaged by the interrupter operating lever 21 during opening movement of the movable contact member I9 after the contact member has opened a predetermined distance less than the full open distance. The predetermined distance is preferably arranged to be suflcient for the arc to have been extinguished before the operating lever 21 engages the plunger 95. The dashpot device 9| acts to retard the final opening movement of the movable contact member I9 before the projection 89 releases the switch latch 95, and thus introduces the desired short time interval between interruption of the circuit and reclosing of the circuit by the switch device 43.

An operating means is provided for restoring the circuit breaker or short-circuit extinguisher to the initial position shown in Fig. 2 after the circuit breaker has interrupted and reclosed the circuit. This operating means comprises an air pressure operated piston 99 movable in a cylinder |Il| for returning the movable contact member 9 to closed circuit position, and a second air pres sure operated piston |03 movable in a cylinder |05 for moving the switch blade 45 to open circuit position. The piston 99 is connected to the operating shaft 23 of the circuit-interrupting device through the agencyl of a piston rod |01, a bell crank lever |99 pivoted to a fixed support III, and a connecting link ||3 which is connected at one end to the bell crank lever |09 and at its other end to a crank arm I I5 rigidly secured to the outer end of the operating shaft 23 outside of the head I1.

The air pressure operated piston |93 Ifor restoring the switch blade 45 to open circuit position is connected to the switch blade through the agency of a piston rod ||1 and a crank arm I I9, which is rigidly secured to the cuter end of the switch operating shaft 41 outside of the head I1. The crank arm I I9 is connected to the piston rod I I1 by a pin and slot connection.

The upper ends of the cylinders IDI and |05 are connected to la source of compressed air (not shown) -by means of air pressure supply conduits |2| and |23. The air pressure is supplied to the cylinders |9| and |05 under the vcontrol of electromagnetically operated valves |25 and |21.

The operating windings |29 and |3| of the electromagnetic valves are energized from the supply lines |33 and |35, which are connected to a source of electrical energy. A circuit |31 connects the operating winding |29 across the supply hnes |33 and |35, and included in series in this circuit is a manual control switch |39. A second circuit |4| electrically connects the operating winding I3I of the switch controlling valve |21 to the supply lines |33 and |35. i

It is important that the opening of the switch blade 45 takes place only after the movable contact member I9 has been returned into engagement with the stationary contact I3, as otherwise an undesirable opening of the circuit will result. For this purpose an interlock switch |43 is included in series in the energizing circuit |4| of the operating winding |3I for the valve |21. The interlock switch |43 is biased open, and is adapted to be closed by a rod |45 connected to the piston 99 only after the piston 99 has moved the movable contact member I9 to the closed circuit position. A second auxiliary switch |44 is included in series in the circuit |4| and this4 switch is biased closed and arranged to be opened when the switch blade 45 is moved to open position.

The operation of the apparatus is briefly as follows: Starting with the parts in the normal lposition illustrated in Fig. 2, let it be assumed that a short circuit occurs in the main circuit. The electromagnetic trip device 13 will be energized a sufficient amount upon the occurrence of a short circuit to move the pivoted latch G3 to released position, eiecting release of the interrupter operating lever 2l'. Upon release of the operating lever 21, the operating spring 59 rotates the lever 21 in a counter-clockwise direction, moving the movable contact member I9 to open circuit position, effecting an interruption of the circuit. During the latter part of the opening movement of the movable contact member I9, the opening movement of the contact member is retarded by the action of the dashpot device 9|, introducing a short time delay before the movable contact member reaches full open position.

. When the movable contact member |9 ap proaches full open position, the cam projection 8'9 on the operating lever 21 engages and releases the switch latch 85, effecting release of the switch blade 45. This position of the parts is illustrated in Fig. S of the drawings in which the cam is releasing the switch latch. As scc-n as the switch blade 45 is released, its operating spring 8| rotates the blade to closed circuit position, eiecting re closing of the circuit 33-35. the parts is illustrated in Fig. 4 of the drawings.

If the disturbance or short circuit is an air short circuit, it will have been completely cleared in a very large percentage of the cases by the time that the switch blade is moved to closed position to reclose the circuit,y and the short-circuit arc will not strike upon reclosing of the circuit.

A single circuit breaker or short-circuit extinguisher, as previously described, can be ar This position of' ranged to protect several outgoing lines, as illustrated in Fig. 1. In this gure, the master circuit breaker is represented diagrammatically at |41 as feeding several outgoing lines |49, |5l, |53 and |55, each of which has its own individual line circuit breaker |51. Upon the occurrence of a short circuit, the master circuit breaker or shortcircuit extinguisher |41 quickly interrupts the circuit and immediately thereafter recloses the circuit by means of the switch blade 45 in air. If the short circuit is an air short circuit, it will have been completely cleared in most instances by the time the circuit is reclosed so that it will not restrike upon reclosing of the circuit. However, if the short circuit still exists upon closing of the circuit, as, for example, if the short circuit is a metallic short circuit, due to foreign bodies or breakage or failure of lines, the line circuit breakers |51 will act to remove the line or part of the system which remains short-circuited.

To restore the circuit breaker or short-circuit extinguisher to its initial position, as shown in Fig. 2, following an operation at which it interrupts and recloses the circuit, the operator closes the manual control switch |39. Closing of the switch |39 effects energization of the operating coil |29 and opening of the valve |25, so that air under pressure is supplied to the upper end of the cylinder |0|. The air pressure moves the piston 99 downwardly to effect a return movement of the movable Contact member I9 to closed circuit position, in which it is held .by the latch 63. As soon as the contact member I9 reaches closed circuit position, the interlock switch |43 is closed by the rod |45 of the piston 99, completing the circuit |4| for energizing the operating coil |3| of the electromagnetic valve |21 for opening the switch. The opening of the valve |21 admits air under pressure to the upper end of the cylinder |05, and the air pressure forces the piston |03 downwardly to effect return of the switch blade 45 to the open position shown in Fig. 2, in which it is reengaged and held by the latch 85. After the circuit breaker or short-circuit extinguisher has thus been restored to its initial or normal position, the operator opens the manual control switch |39, deenergizing the control circuit |31. When the circuits |31 and IM are dee'nergized, the valves |25 and |21 return to their normal closed positions in which they shut off the supply of air pressure and also connect the cylinders I0! and |535 with the outside atmosphere through the exhaust lports of the valves.

Under certain circumstances, it may be advantageous to provide an additional control device for the circuit breaker or short-circuit extinguisher, by the operation of which the switch blade 45 is retained in open circuit position to prevent immediate reclosing of the circuit. This additional control 'device |58 (Fig. 2) permits the use of the circuit breaker for disconnecting purposes or for a later reclosing operation.

If desired, the time interval between interruption of the circuit by the interrupting device and reclosing of the circuit by the switch blade may `be shortened by eliminating the dashpot device 9|, and arranging the position of the releasing cam 8B to suit the particular requirements as to the speed of reclosing.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes mayA be made therein without departing from the spirit of the invention. It is desired, therefore, that the appended claims be given the broadest reasonable construction that is permissible in the light of the prior art.

I claim as my invention:

l. A device for interrupting and automatically reclosing a circuit comprising, a circuit interrupter having a pair of interrupting contacts, means biasing said contacts open, latch means for releasably holding said contacts closed, a second pair of air break contacts structurally associated with said interrupter and electrically connected in the circuit in shunt relation to said interrupting contacts, means biasing said second pair of contacts closed, a second latch means for releasabl'y holding said second pair of contacts open, current responsive means operable upon the occurrence of predetermined abnormal conditions in the circuit to release said firstmentioned latch means to cause opening of said interrupting contacts to interrupt the circuit, means operable a short-time interval after interruption of the circuit for releasing said second latch means to cause said second pair of contacts to reclose the circuit, and means operable to cause return of said interrupting contacts to closed and latched position while said second pair of contacts are in closed position and for causing return of said second pair of contacts to open and latched position after said interrupting contacts have engaged.

2. An electrical system comprising apower bus, one or more feeder circuitsV adapted to'be fed from said power bus, an individual circuit breaker in each feeder circuit, a short circuit extinguisher connecting said power bus to said feeder circuits comprising a pair of circuit interrupting contacts normally held closed, a second pair of contacts connected in shunt relation to said circuit interrupting contacts and normally held open, means operable in` response to a short circuit condition in the system for causing said circuit interrupting contacts to open and thereby interrupt the circuit feeding said feeder circuits, and means operable in response to opening of said circuit interrupting contacts forl causing said second pair of contacts to close and thereby reclose the circuit, said second pair of conta-cts remaining closed to feed current to said feeder circuits even though the shortcircuit condition still exists upon reclosure of the circuit, and resetting means operable to reset said circuit interrupting contacts to closed position while said second pair of contacts are in closed position and thereafter reset said second pair of contacts to open position.

3. Electrical switching apparatus for controlling an electrical circuit comprising a circuit interrupter having a fixed contact and a cooperating movable contact and arc extinguishing means, operating means for said circuit interrupter, an air break switch structurallyassociated with said circuit interrupter and electrically connected in shunt relation to said interrupter contacts by relatively short electrical4 ing said switch operating means to initiate closing operation of said switch.

4. A device for interrupting and automatically reclosing a circuit comprising, a circuit interrupter having relatively movable contacts, an air break switch structurally associated with the interrupter and electrically connected in parallel with said interrupter contacts, said switch having a movable contact mounted for movement independently of the movable contact of the inter rupter, means for normally holding said switch open, mechanical actuating means for opening said interrupter contacts, separate actuating means for closing said switch, means operable upon the occurrence of predetermined abnormal conditions in the circuit for causing said interrupter actuating means to open said interrupter contacts to interrupt the circuit, and means operable after said interrupting contacts have opened a predetermined distance for causing said switch actuating means to close said switch to reclose the circuit, and means operable to reset said actuating means to close said interrupter contacts while said switch is closed, and open said switch after said contacts have engaged.

5. Electrical switching apparatus for controlling an electrical circuit, comprising a circuit interrupter having a pair of circuit-interrupting contacts biased open, arc-extinguishing means for said contacts, means releasably holding said contacts closed, a second pair of contacts structurally associated with the interrupter and electrically connected in shunt relation to said interrupting contacts by relatively short electrical connections, means biasing said second pair of contacts to closed position, latch means releasably holding said second pair of contacts open, means operable upon the occurrence of predetermined abnormal conditions in the circuit for releasing said interrupting contacts to cause opening thereof to interrupt the circuit, and means movable with said circuit interrupting contacts operable after interruption of the circuit by said interrupting contacts to mechanically release said latch means to release said second pair of contacts to cause reclosinf,r of the circuit thereby.

6. A device for interrupting and automatically reclosing a circuit comprising, a circuit interrupter having a pair of circuit-interrupting contacts, means biasing said contacts open, means releasably holding said contacts closed, a second pair of contacts structurally associated with the interrupter and electrically connected in the circuit in shunt relation to said interrupting contacts by relatively short electrical connections, means biasing said second pair of contacts closed, means releasably holding said second pair of contacts open, means operable upon the occurrence of predetermined abnormal conditions in the circuit for releasing said interrupting contacts to cause opening thereof to interrupt the circuit, means operable a short time interval after interruption of the circuit by said interrupting contacts to release said second pair of contacts to cause reclosing of the circuit thereby, and means operable to return said interrupting contacts to closed position while said second pair of contacts are closed, and to return said second pair of contacts to open position after said interrupter contacts have engaged.

'7. Electrical switching apparatus for controlling a circuit, comprising, a circuit interrupter having relatively movable interrupting contacts biased open, means releasably holding said contacts closed, a second pair of contacts structurally associated with the interrupter and electrically connected in shunt relation to said interrupting contacts by relatively short electrical connections, said second pair of contacts being biased closed, means releasably holding said second pair of contacts open, current responsive means operable upon the occurrence of a short circuit in the circuit to cause release of said interrupting contacts to eiect opening thereof, and means operable upon said interrupting contacts reaching open position for causing release of said second pair of contacts to eiect reclosing of the circuit irrespective of the electrical condition of the circuit.

WERNER KAUFMANN. 

